Embodiments of the present application generally relate to permanent magnet motors. More particularly, but not exclusively, embodiments of the present application relate to mechanical fixation of permanent magnets within a rotor construction for high speed permanent magnet motors.
Adhesives, including epoxy adhesives, are often utilized to secure magnets to the rotors of high speed permanent magnet motors. Yet, the process of securing magnets to rotors via use of adhesives may be relatively time consuming and laborious, and thus expensive. For example, adhesives typically require a hardening or curing time, such as, for example, a hardening period of around 24 hours. Additionally, the adhesive layer that forms underneath and/or between the magnets may adversely impact the quality of the rotor surface, and thereby necessitate the additional step, and associated time and expense, of grinding the magnet surfaces. Adhesives may also be inappropriate and/or unreliable in at least some high speed applications. For example, the bonding strength provided by a cured adhesive may be insufficient to withstand, or otherwise be compromised when subjected to, the forces generated by repeated, relatively high velocity rotational displacement of the rotor.
Additionally, eddy current shields are typically not utilized in permanent magnet rotor applications, as the relatively high temperatures generated by eddy currents are often controlled through the use of coolant solutions and/or may be withstood by the use of relatively high thermal load materials in the construction of permanent magnet rotors. Yet, the inclusion of coolant systems and use of high thermal load materials can increase the complexity and/or the cost of systems that utilize permanent magnet rotors. Additionally, similar to the magnets, eddy current shields, if used, are typically secured to the rotor via an adhesive or screws. Yet, eddy current shields that are secured to a rotor via an adhesive may suffer from the same reliability issues as magnets, particularly in high motor speed applications. Further, securing eddy current shields to a rotor with screws may further increase the time and effort involved in the construction of the rotor, and thereby further elevate the costs associated with rotor construction.